def reverse(self, phoneb):
'''(PhoneBook,PhoneBook) -> PhoneBook
Reverse the contacts from the phonebook that are present in the
alphabetical order
REQ: List must be given'''
# create empty sll to return the reversed link
rev = SingleLinkedList()
# if the reversed sll is empty
if (rev.get_head() is None):
# create a node and set the element from given phonebook
new = Node(phoneb.get_head().get_element())
# set the node head
rev.set_head(new)
# Traverse through the given phonebook and continue traversing
# through the list
curr = phoneb._head.get_next()
while (curr is not None):
new = Node(curr.get_element())
rev.add_first(new)
curr = curr.get_next()
# return the reversed phonebook
return rev
def reversed_phonebook(self):
'''(PhoneBook) -> PhoneBook
Returns the phonebook of the contacts in the reverse order from the
phonebook of the alphabetical order
REQ: phonebook must not be empty'''
# create the empty sll for reverse contacts
rev = SingleLinkedList()
# if the reverse phonebook is empty
if (rev.get_head() is None):
# create a new node and add that element in reverse phonebook
new = Node(self.get_head().get_element())
# set that node as a head of the reverse phonebook
rev.set_head(new)
# traverse through the list & keep adding the contact in rev phonebook
curr = self._head.get_next()
while (curr is not None):
# create empty node and add the element in it
new = Node(curr.get_element())
# keep adding notes in the front in rev phonebook
rev.add_first(new)
# continue traversing through the list
curr = curr.get_next()
# return the reversed phonebook
return rev